1. Field of the Invention
The present invention relates generally to a device for use with a computer for manual tracing of complex graphic curves and profiles from a drawing or the like which are simultaneously transferred into computer memory and, more particularly, to a device for use with a standard computer display controller to enable highly accurate translation of such complex curves and profiles from a drawing or photograph into computer memory.
2. Description of the Prior Art
With the proliferation of relatively inexpensive personal computers has come a strong demand for accessories for these computers enabling them to be used for an increasing number of tasks. Whether the application is for computer-aided design, complex mathematical analysis, or more mundane applications such as copying a drawing or a picture for display on a computer monitor, a popular activity with such personal computers is the transfer of a complex curve or profile from a drawing or photograph directly into computer memory by means of manually tracing the curve or profile from the drawing or photograph.
There are basically three types of devices which are capable of manually translating curves and profiles from a sheet of paper to the computer memory for filing, display, or printout, and these systems are the dedicated resolving system, the tablet type drawing system, and a computer cursor controller known as a "mouse".
The first of these types of systems, the dedicated resolving system, has been around for some time, and is illustrated by U.S. Pat. No. 2,889,627, to Culpepper et al, and more recently by U.S. Pat. No. 4,331,954, to Bauman et al. The dedicated resolving system typically includes a complex electromechanical linkage system mounted on a tracing board and requires a complex sysem interface between the resolving system and the computer. Such systems are simply not practical for the use contemplated herein due to their high purchase price, which is easily several times the cost of the entire personal computer system.
The second type of system is the tablet type system, which is illustrated by U.S. Pat. No. 4,318,096, to Thornburg et al, as well as by U.S. Pat. No. 2,586,160, to Handel. The tablet type system may include either a small, portable tablet having an electrically sensitive surface or a larger, dedicated electrical table surface in which a curve or shape is inputted by use of a dedicated electrical pen. Various adaptations of this system exist, including those in which the user's finger may be used instead of a pen, as well as those systems utilizing light pen or torch screens.
The main drawbacks of such systems is that they are generally not very accurate unless they are also quite expensive. In addition, the use of such systems to trace curves or profiles from a drawing or photograph rather than directly on the tablet would either be substantially difficult or completely impossible, depending on the system. It is therefore evident that the tablet type system is not a practical solution to the unique requirements of the present design problem.
A third type of system experiencing rapidly increasing popularity utilizes a computer cursor controller device known as a "mouse". A mouse is a pointing device generally for use with a visual display system or printout, and a transducer contained in the mouse converts translational motion of the mouse housing into a position signal which controls the movement of a cursor visually displayed on the computer monitor. By moving the mouse over a flat surface in the desired direction, the cursor will precisely follow the translation of the mouse.
The mouse typically contains a switch which is utilized to initiate a particular desired function. One of the functions personal computers are capable of performing with the mouse is generally known as the "paint" function. This function allows the computer operator to sketch images on the monitor by simply moving the mouse over the flat surface in the desired direction or directions, thereby making the mouse in effect a sort of pencil with which a drawing may be made to appear on the monitor. One such system also provides the capability of "drawing" straight lines and predefined curves and shapes on the monitor screen, according to shapes which are stored in the computer. However, this system is not able to reproduce complex curves and shapes with the accuracy that is desired.
It will be appreciated that the translation of complex curves and shapes from paper images to computer images is numerically very difficult to accomplish with any degree of accuracy, and the mouse has therefore become a popular device for performing such a function. The mouse typically contains a rotating ball and two optical sensors translating movements of the mouse to electrical signals to drive the cursor in the direction the mouse is moved. Another type of mouse utilizes only optical sensing of a grid-marked surface, but this type of mouse (which is shown in U.S. Pat. No. 4,364,034, to Kirsch) requires a grid-marked surface, which requirement may not be practical when copying figures on drawings or photographs.
Although the mouse goes a long way toward satisfying the need for a device enabling the translation of a complex image from a drawing to a computer, the mouse unfortunately has an inherent deficiency which makes highly accurate tracings of complex curves and profiles virtually impossible. This is inherent in the conventional use of the mouse, because the part of the mouse which acts as the actual pointer is the ball, which is centrally located underneath the mouse. It may immediately be appreciated that since the actual pointer of the mouse is underneath and in the center of the mouse, it is very difficult to trace with any degree of accuracy a curve or shape by moving the ball directly over the counter of the curve or shape.
A point on the side edge of the mouse can be used as the pointer, but since this location is offset from the ball of the mouse, which is the actual pointer, tracing done using this edge point will not be accurate unless the mouse is maintained in a fixed directional orientation while it is moved along the contours of the curve or drawing. What this means is that if the racing is commenced with the mouse pointed directly toward the top of the paper, the mouse must remain pointing directly toward the top of the paper while the tracing is manually performed. Failure to so orient the mouse will result in substantial error in the traced copy stored in the computer memory.
It may therefore be appreciated that there exists a substantial need for a device for use with the mouse which will automatically maintain the mouse in the desired orientation while the tracing process is carried out. The device must not get in the way of the tracing operation, and it must be adaptable to fit a presently existing mouse to avoid obsoleting all such devices sold prior to the existence of the present invention. This design, which will enable highly accurate tracings to be made with any mouse-computer combination, should also be inexpensive in order to afford the broadest possible market to personal computer owners.